Transcription in the mammalian (mouse) brain will be examined in terms of various classes of RNA, cell types and anatomical regions. The complexity of poly(A)mRNA populations relative to various anatomical regions of brain will be examined. The relationship between high molecular wt. nuclear RNA to poly(A)mRNA will be studied. Nuclear RNA from neurons and various glial cells will be compared in terms of sequence diversity and overlap. These and other experiments are intended to provide basic information regarding the transcriptional utilization of the genome and provide some basis for determining the presence and number of brain specific mRNAs. Also this work will be utilized as a reference for future studies on early postnatal development of the mammalian brain. BIBLIOGRAPHIC REFERENCES: J.A. Bantle and W.E. Hahn. Complexity and characterization of poly-adenylated RNA in the mouse brain. Cell 8:139, 1976. J.A. Bantle, I.H. Maxwell and W.E. Hahn. Specificity of oligo(dT)-cellulose chromatography in the isolation of polyadenylated RNA. Anal. Biochem. 72:413, 1976.